Lift Cylinder; Description; Maintenance - Manitowoc Grove RT765E-2 Service And Maintenance Manual

HYDRAULIC SYSTEM

LIFT CYLINDER

Description

The lift cylinder Figure 2-36 has a bore of 12.0 in (30.5 cm).
The retracted length of the cylinder from the center of the
barrel bushing to the center of the rod bushing is 116.0 in
(294.6 cm). The extended length of the cylinder from the
center of the barrel bushing to the center of the rod bushing
is 205.6 in (522.2 cm). Its stroke is 89.6 in (227.6 cm).
A wiper ring prevents foreign material from entering the
cylinder. O-rings and other seals prevent internal and
external leakage.
The cylinder weighs approximately 1634 lb (741 kg).

Maintenance

Disassembly
NOTE: Any maintenance requiring disassembly of the
cylinders should include replacement of all seals
and rings. A seal kit will supply the required items.
1. Disconnect the tube assembly from the holding valve.
2. Remove the capscrews and washers securing the
holding valve. Remove the holding valve from the
cylinder barrel.
3. Remove the socket head cap screws securing the head
retainer ring to the head.
4. Using a spanner wrench or chain wrench, unscrew the
head retainer ring from the barrel.
Do not use air pressure to remove the rod. Use only a
source of controlled hydraulic oil pressure if the rod is
hard to move. Injury may result from the cylinder rod
unexpectedly exiting the cylinder barrel.
CAUTION
Exercise extreme care when handling or setting down the
rod. Damage to the rod surface may cause unnecessary
maintenance and expense.
5. Remove the rod and attached parts from the barrel.
NOTE: Cover the barrel opening to avoid contamination.
2-64
CAUTION
Published 9-04-2014, Control # 422-08
RT765E-2 SERVICE MANUAL
CAUTION
When removing seals and rings, avoid scratching the
grooved and gland surfaces.
6. Remove the two hydrolock seals from the outside of the
piston.
NOTE: Arranging discarded seals and rings in the order of
disassembly will aid in installation of new seals and
rings. Pay attention to how each seal and ring is
installed to avoid installing replacement seals and
rings improperly.
7. Remove the setscrew securing the piston to the rod.
8. Unscrew the piston from the rod.
9. Remove the piston seal from the inside of the piston.
10. Remove the head from the rod.
11. Remove the o-ring and backup ring from the outside of
the head and the wear rings, buffer seal and deep Z rod
seal from the inside of the head.
12. Remove and discard the two threaded inserts from the
head.
13. Remove the head retainer ring from the rod.
14. Remove the wiper ring and backup ring from the inside
of the retaining ring.
Inspection
1. Clean all parts with solvent and dry with compressed air.
Inspect all parts for serviceability.
2. Inspect the barrel carefully for scoring. If barrel is
scored, it must be repaired or replaced.
3. Check piston for damage. If piston is damaged,
determine if it can be repaired or must be replaced.
4. Inspect rod for straightness. Determine if it can be
straightened or must be replaced.
CAUTION
Before installing new seals and rings, clean all surfaces
and carefully remove burrs and nicks. Parts displaying
excessive wear or damage should be replaced.
5. Stone out minor blemishes and polish with a fine crocus
cloth.
6. Clean with solvent and dry with compressed air any
parts that have been stoned and polished.